The Survey of Income and Program Participation (SIPP) is a nationally representative survey that provides longitudinal surveillance on health insurance coverage at a monthly level, requiring a complex system of survey administration and data processing. This analysis presents new longitudinal health insurance estimates from the SIPP spanning May 2008 to March 2010. I present estimates of the number of months of insurance, as well as monthly estimates for coverage types,by age group. I then decompose these estimates into their constituent waves and subsample components, to reveal any irregularities embedded within the aggregate numbers.